1. Field of the Invention
Aspects of the present invention relate to an electrophotographic image forming apparatus. More particularly, Aspects of the present invention relate to a process cartridge for an image forming apparatus.
2. Description of the Related Art
An electrophotographic image forming apparatus uses a process cartridge. The process cartridge includes an electrophotographic photosensitive drum and related processing mechanisms and is adapted to be detachably mountable as a unit in a main body of the electrophotographic image forming apparatus. The process cartridge is an easily replaceable cartridge that packages components having substantially the same service life such as various rollers constituting the photosensitive drum and a developing unit and a predetermined amount of toner.
The process cartridge B and electrophotographic image forming apparatus 100 using the cartridge B are illustrated in FIGS. 1 to 3. FIG. 1 shows the configuration of a conventional image forming apparatus 100. FIG. 2 is a perspective view showing the external appearance of a process cartridge B of FIG. 1. FIG. 3 is a sectional view showing the internal configuration of the process cartridge B. Referring to FIGS. 1 to 3, the process cartridge B is detachably mounted in a main body A of the image forming apparatus 100. In the image forming apparatus 100, a photosensitive drum 111 is charged by a charge roller 112, and an electrostatic latent image is formed on the surface of the photosensitive drum 111 by a laser beam L from a laser scanning unit 130. The electrostatic latent image is developed into a desired visible image with toner transported from a toner chamber 118 by a supplying roller 115 in response to rotation of the photosensitive drum 111. The developed visible image is transferred to a sheet of recording paper P passing between the photosensitive drum 111 and a transferring roller 140.
In a cartridge frame 110 of the process cartridge B, the toner chamber 118 is provided at one side of the photosensitive drum 111, and a waste toner chamber 123 is provided at the other side of the photosensitive drum 111. Around the toner chamber 118, a developing roller 114, the supplying roller 115, a doctor blade 116 and an agitator 117 are installed in sequence and are supported by a main frame 119. Around the waste toner chamber 123, the charge roller 112, a cleaning blade 121 and the like are installed in sequence and are supported by a cleaning frame 124. The cleaning blade 121 is attached to a cleaning support member 122. However, in the process cartridge B, because a bent portion 122a of the cleaning support member 122 is bent towards the photosensitive drum 111, a beam inlet 131 for the laser beam L from the laser scanning unit 130 is too narrow. In particular, as shown in FIG. 3, in the image forming apparatus provided with a cleaning roller 113 and the charge roller 112, the end of the bent portion 122a may contact with the charge roller 112 or the cleaning roller 113. Consequently, to allocate a sufficient space for the beam inlet 131 of the laser scanning unit 130, the size of the developing roller 114 must be increased, complicating a space allocation problem in the process cartridge B. To solve this space allocation problem, an image forming apparatus adopting an enhanced process cartridge B′ has been disclosed in U.S. Pat. No. 6,836,639.
FIG. 4 is a sectional view showing the internal configuration of the process cartridge B′ disclosed in U.S. Pat. No. 6,836,639, and FIG. 5 is an enlarged view showing a cleaning frame 124 of FIG. 4. Referring to FIGS. 4 and 5, in the process cartridge B′, a waste toner chamber 123 includes a first cleaning frame 124a and a second cleaning frame 124b on the first cleaning frame 124a, and the first cleaning frame 124a and second cleaning frame 124b are interconnected by a reinforcement member 125 to prevent deformation of the cleaning frame 124. A bent portion 122a of a cleaning support member 122 supporting a cleaning blade 121 is bent away from the photosensitive drum 111 towards the cleaning frame 124 (to the left in FIG. 4). In the process cartridge B′ having this structure, the overall strength of the cleaning frame 124 is enhanced, and a waste toner space for containing waste toner T is expanded because the reinforcement member 125 is disposed above the bent portion 122a. However, in the process cartridge B′, the second cleaning frame 124b is separately installed on the first cleaning frame 124a, and the first cleaning frame 124a and the second cleaning frame 124b are welded together, then interconnected by the reinforcement member 125. Even though the reinforcement member 125 is disposed above the bent portion 122a of the cleaning support member 122, the bent portion 122a and the reinforcement member 125 themselves take up some part of the waste toner space.